The present invention relates generally to laser device fabrication, and more particularly, to a method and apparatus for transporting laser bars, e.g., from a facet coat holding fixture.
Semiconductor laser devices such as double heterostructure laser diodes are utilized in a variety of applications such as for optical sources in fiber optic communications. In the manufacture of such devices, double heterostructures are grown and processed on a wafer substrate by, for example, liquid phase epitaxy. The wafer is then cleaved into typically solid rectangular laser bars containing many laser diodes. Since, at the laser bar level, the laser diodes are functional, testing is often performed at this level prior to dicing the individual laser diodes from the bars.
Each laser bar has two end faces (facets) formed by cleaving during the cleaving process. Ultimately, laser light is transmitted through these facets, so it is important for their surfaces to remain unperturbed during subsequent handling. As such, the laser bar should be handled via contact with its longitudinal outer surface rather than the facet surfaces. Following the cleaving operation on the wafer to form the laser bars, the facets are coated with an optical coating while being held in a facet coat holding fixture. Due to the small size of the laser bars (e.g., typical dimensions on the order of 0.005.times.0.012.times.0.30 inches), the removal of the laser bars from the holding fixture is a delicate process. A manual removal method may be employed in which an operator manually positions a vacuum pick in proximity to the bar. The bar is temporarily held against the surface of the vacuum pick by suction, thus allowing the operator to transport the bar to a desired location. The vacuum is then turned off and the bar placed down on a surface. While often satisfactory, a drawback to the manual method is the uncertainty in yield due to the skill level of the operator.
Automatic methods of laser bar removal from facet coat holding fixtures have also been developed. Typically, these methods employ a sophisticated robot arm to handle the laser bars, rendering the process costly and complex.
Accordingly, there is a need for a relatively simple automatic laser bar removal and transporting process that is conducive to high yields. The present invention addresses this need.